1. Field of the Invention
The present invention generally relates to an optical disc drive apparatus and, more particularly, an optical disc drive apparatus of a type having a disc changer capability for recording and/or reproducing information on and from a selected one of a plurality of optical discs resting on drawable subtrays stacked on a main tray.
In particular, the optical disc drive apparatus of the present invention is suited for use in a personal computer and is so sized and so configured as to permit an existing single disc drive in the personal computer to be replaced with it
2. Description of the Prior Art
With the advent of the age of personal computers, CD-ROM drives have come into widespread use as a computer peripheral device and are now standard with a majority of the computers. In addition, it is not rare for a single computer user to have a number of optical discs in possession. In this context, user demands are now increasing for CD-ROM drives having an automatic disc changing capability by which a plurality of optical discs can be loaded automatically one at a time to a position where access is made by an optical information read-out device.
On the other hand, in most of the desk-top personal computers, a CD-ROM drive or any other disc drive is installed in a housing space generally known as a "5-inch bay". The opening leading to this housing space is of a standard size generally known as a "5-inch half-height" size, and any peripheral device that is desired to be accommodated in the 5-inch bay must have a maximum size of 146 mm in width and 41.3 mm in height. Accordingly, a CD-ROM drive having a built-in automatic disc changer must also satisfy the size requirement if it is desired to install it in the 5-inch bay. If indiscriminate design is made to allow the drive apparatus to accommodate an increased number of optical discs, the resultant drive would no longer satisfy the size requirement.
In any event, the CD-ROM drive having an automatic disc changing capability and satisfying the size requirement, i.e., capable of being installed in the 5-inch bay, is well known in the art. By way of example, Japanese Laid-open Patent Publication No. 3-216857, published Sep. 24, 1991, discloses an optical disc drive apparatus comprising a main tray supported for movement between withdrawn and inserted positions relative to the drive housing and having a plurality of subtrays stacked thereon, each for supporting thereon an optical disc. This optical disc drive apparatus is so designed that when the main tray is moved to the inserted position with the stacked subtrays held consequently at a stand-by position, a selected one of the subtrays then held at the stand-by position can be drawn towards a loaded position where the optical information read-out device accesses the optical disc resting on such selected subtray.
According to this publication, the main tray is formed with grooves for holding the subtrays in equidistantly spaced relation to each other. When the optical disc resting on an arbitrarily chosen one of the subtrays then held at the stand-by position with the main tray held at the inserted position is desired to be removed or replaced with a different optical disc, the main tray carrying the entire number of the subtrays must be withdrawn to the withdrawn position so that the optical disc on the arbitrarily chosen subtray can be removed. After this removal has been made, the main tray must again be moved to the inserted position.
A similar optical disc drive apparatus is also disclosed in Japanese Laid-open Patent Publication No. 6-259865, published Sep. 16, 1994. This known apparatus makes use of an elevating stocker positioned on one side of a disc playback position remote from the withdrawn position for the main tray and is so designed and so configured that, after a tray with a carriage or subtray thereon has been moved to the inserted position, the optical disc resting on the carriage or subtray is drawn to a playback position where it is played back. The optical disc having been played back is then transported together with the subtray towards the elevating stocker where it is accommodated. The stocker disclosed therein has a capacity to accommodate a plurality of, for example, 7, subtrays and, accordingly, by stacking the subtrays, each having an optical disc resting thereon, within the stocker, an arbitrarily chosen one of the subtrays can be drawn to the playback position that is defined intermediate between the inserted position for the tray and the stocker.
According to this second-mentioned publication, separate drive motors are required for driving the tray and for selectively lowering and lifting the stocker. In addition, the stocker is supported by a movable member and, therefore, when an impact acts on the apparatus during, for example, transport of the apparatus, not only may lifting pins be disengaged from the stocker, but also the movable member may be damaged.
Japanese Patent Publication No. 6-14423, first published Nov. 25, 1982, under Laid-open Publication No. 59- 96559, discloses a magnetic disc drive apparatus including a magnetic disc drive device for transporting a disc-shaped recording medium to a loading position at which the recording medium is mounted on a rotary drive within a housing and a forced ejector with which the recording medium then held at the loading position can be manually forcibly removed.
The teachings of this publication No. 6-14423 may be employed in the optical disc drive apparatus disclosed in the previously mentioned publication No. 3-216857 so that, in the event of, for example, an electric power failure occurring when the main tray having the subtrays stacked thereon is moved at least to the inserted position, the subtrays can be manually forcibly removed out of the drive housing together with the main tray. In this resultant apparatus, it may be contemplated to manually rotate an output shaft of the drive motor used to drive an arbitrarily chosen one of the subtrays then held at the stand-by position towards the loaded position or to manually forcibly drive the output shaft of the motor used to drive the main tray between the withdrawn position and the inserted position. However, where the drive of the motor is transmitted by the use of a pinion and a worm gear meshed with such pinion, such as disclosed in the publication No. 6-14423, a relatively large manipulating force would be required, resulting in reduction of the operability.
Japanese Laid-open Utility Model Publication No. 5-96936, published Dec. 27, 1993, discloses a design in which the space between neighboring subtrays stacked on the main tray exhibited when the main tray is moved to the stand-by position is minimized to render the apparatus as a whole to have a reduced height, but in which the space between the neighboring subtrays when the subtrays positioned between those neighboring subtray has been moved to the loaded position with a part thereof situated between such neighboring subtrays, is expanded to allow the optical disc to be rotated within such space.